It's obviously quite complicated as you can see from the links I posted, and not simply a matter of the EU stealing our fish. There's quotas on fish (agreed to by the UK fwiw) for the purpose of sustainability. These aren't unique to the EU but also involve global agreements because of overfishing.

There's also agreements about where different nations can fish; it's not that the Dutch suddenly got given access to UK waters and now they're getting rich off our back, they've historically been in those waters all along.

There's also, as pointed out, historical factors at play that mean that laborer jobs aren't able to sustain the relative standard of living they used to be able to. People don't want to work in shitty pay dangerous jobs when they have better opportunities elsewhere.

Again, I sympathize with these people, I'm sorry if they're suffering. I just don't feel like I should take it on the chin for something that may or probably won't help them.